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06-25-2019, 12:59 AM | #1 |
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Piston ring gaps - new Manley too loose?
99.55mm Manley 2618 pistons and included rings, piston to wall .0035
Out of the box they end up with .023 top, .025 second gaps on cyls 1/2 and .024 top, .026 second on cyls 3/4. Too loose? I had advice to set them at .020/.024. Calling Manley in the AM, curious what you guys think.
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06-25-2019, 11:56 AM | #2 |
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Manley tech referred me to Total Seal tech.
He said if anything he’d run looser gaps than what I have already. I’m gonna leave them and send it |
06-25-2019, 03:52 PM | #3 |
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how much power are you planning to make?
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06-25-2019, 04:14 PM | #4 |
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350-420 wheel on 21-23psi pump, built to later take 500+ and 30psi on E or race gas. Open deck but real rods, ARP2000 studs, JE Proseal Athena head gaskets.
Edit: measurements sans torque plates Last edited by nucci; 06-25-2019 at 07:48 PM. |
06-25-2019, 10:03 PM | #5 |
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A bunch of searching around here is leading me to believe that a .018 top ring would be a lot better idea, question is how much ...
May be ordering 99.75 rings tomorrow. |
06-25-2019, 10:49 PM | #6 |
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06-25-2019, 11:20 PM | #7 |
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Big difference between E85 and gasoline style fuels/race gas. I think with the E85 a little tighter is fine because of the residual cooling,
but with race/gasoline fuels it will get hotter (piston will expand more) and need a larger gap, given the same output |
06-25-2019, 11:37 PM | #8 |
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Decision made - oil rails are .033 to .040, way too big. Getting 99.75 rings.
PSA: 99.55mm pistons are weird for rings |
06-26-2019, 11:40 AM | #9 |
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i also agree with this.
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06-27-2019, 08:04 AM | #10 |
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Makes it a bit tougher if you build a motor for flex fuel then I guess.
Well you'd probably either have to run with more blowby... or just make sure your gas tune is really turned down. |
06-27-2019, 10:50 AM | #11 |
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So, just curious, what's a good range for ring gap using flex fuel and sub 450 whp? I was looking at CP's instructions and they're recommending .021 for the top and .023 for the bottom using the turbo sized gap formula.
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06-27-2019, 11:46 AM | #12 | |
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Quote:
Now, those measurements will also depend upon the power goals as well along with piston material and a bunch of other stuff. |
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06-02-2020, 07:04 PM | #13 | |
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Quote:
Also, what's your thoughts and experience with Gap-less second ring? |
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06-03-2020, 12:47 PM | #14 | |
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Quote:
If you're going to be sub-450 I would like to see something just a skoosh tighter on the rings, but honestly I wouldn't have a problem with .018, but do watch fuel dilution. I have not played with the gapless second, but I have played with the gapless top on a Subaru. I REALLY liked it, BUT there's a couple of things. 1) Absolutely follow their gapping instructions (I think they spec .0065 per inch of bore - second guessing them my first time I tried it led to failure) and 2) my experience was in a race motor so I cannot tell you any results from long term use. |
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06-03-2020, 01:12 PM | #15 |
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I'm targeting 0.0196 and 0.0216 for gaps. which is what JE recommends.
450-500 whp on E85. high boost |
06-03-2020, 01:44 PM | #16 | |
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Quote:
What benefits do you see with running either/both gapless top and second ring? |
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06-03-2020, 07:21 PM | #17 | |
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Quote:
The compression and leakdown was absolutely awesome on the gapless top ring. Like amazingly so. Sadly I believe that motor met it's demise with a broken valve spring... I can't remember which track that was at. I want to say it was Mid-ohio on that one. It was a number of years ago. |
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